Anyone else think this is an incorrect way to measure the roadworthyness of a used car?

No, much more wear and tear is done to an engine with constant short journeys than long, so emissions can suffer. Brakes can bind through lack of regular use, exhausts can rust through due to condensation building up thanks to the system never getting hot enough to to dry it out properly, suspension components can fail through drving constantly through the battlescarred town/city roads (motorway surfaces may not be great compared to some other countries, but they are much better than our urban roads.

That isn't to say higher mileage cars are not likely to suffer, but overall i'd say it balances out pretty well. If anything, just have all cars MOT'd every year from new.

Parts and settings deteriorate over time as well as mileage. That is why most manufacturers specify service intervals as a combination of miles and time. So if you are worried about safety the first MoT should logically change to something like 3 years or 36k miles, whichever comes first.

A two year old car can easily travel 80k without a legal road safety test. But a three year old car could travel less than 20k and be forced the test.

You could make an argument for 3yrs OR 60,000 miles but not mileage alone.

Cars have come on since the sixties but c1970 my Mother had a 1966/D Mini with <20k miles and you could see the road through it's floor.

I'd rather not create an extra incentive for people to clock the mileage on their cars!

I hear too many tales of people taking out a PCP for 8,000 (or so) miles a year and doing 20,000+ as it is.

Edited by Will deBeast on 01/02/2020 at 05:30